HOUSTON - The crew members aboard the International Space Station were busy this week with handover operations from the Expedition 14 residents to the newly arrived Expedition 15 crew.

Expedition 15 Commander Fyodor Yurchikhin and Flight Engineer Oleg Kotov arrived at the station Monday after a Saturday launch from the Baikonur Cosmodrome in Kazakhstan. With them on their Soyuz TMA-10 spacecraft was Spaceflight Participant Charles Simonyi, a U.S. businessman flying under a contract with the Russian Federal Space Agency.

Williams, who has served as an Expedition 14 crew member since December, will remain on the station providing Expedition 15 with an experienced flight engineer for the early part of its mission. She is scheduled to return home aboard space shuttle Endeavour this summer.

Lopez-Alegria and Tyurin are scheduled to return home in their Soyuz TMA-9 spacecraft April 20. Simonyi will return with them after spending approximately 11 days aboard the station.

Crews performed required station maintenance and spent considerable time on scientific studies. Those activities began with time-critical transfer of several experiments from the newly arrived Soyuz to the station and station power.

On Tuesday, Tyurin conducted the Russian experiment Bioemulsion, an effort to develop technology to produce microorganisms safely for bacterial, fermental and medical preparations.

On Wednesday, Kotov set up the European Exhaled Nitric Oxide-2 experiment, which measures nitric oxide exhaled before and after spacewalks. Its objective is to better understand the potential for decompression sickness.

Meanwhile, Tyurin worked with the Russian Pilot experiment, which is designed to measure the long-duration spaceflight changes in a crew member's ability to pilot a spacecraft.

On Thursday, Lopez-Alegria spent more than three hours resizing U.S. spacesuits for future users. The suits were worn on an unprecedented series of three station spacewalks during a nine-day period beginning Jan. 31.

Throughout much of the week, beginning with the crew news conference on Tuesday, crew members took breaks to talk with news media representatives, including ABC News, Space.com, CNN, and CBS.

The crew planned to eat on Friday a special Martha Stewart-catered meal of quail, duck, rice pudding and dried fruits.

Additionally, both crews performed their regular exercise sessions this week. These sessions are particularly important for Lopez-Alegria and Tyurin, who will soon return to Earth and the effects of gravity.

Williams is scheduled to run the Boston Marathon using a station treadmill Monday at 9 a.m. CDT to coincide with the race on the ground. This will be the first time an astronaut in space is an official participant in a marathon.